I DIDN’T need the weatherman on ABC television to tell me that a cold snap was on the way which would dump snow on the streets of Hobart.
The black cockies were coming down from Mt Wellington about four days before the rare snow event at the start of this month. It was in fact the same day as weatherman Simon McCullock’s prediction that snow was arriving in coming days.
According to southern Tasmanian folklore, the sight of yellow-tailed black cockatoos arriving in the suburbs of Hobart, Glenorchy and Kingston always foretells blizzards on the mountain and its foothills. I’ve never been able to work out whether this is accurate or not, but certainly I can always tell when cold weather is on the way from the antics of the resident birds in my garden.
For a start, they refuse to sing, and if I study them closely I find they tend to restrict their movements. In cold weather, when fragile feathered bodies need all the heat and energy they can get, my garden birds seem to know that singing and unnecessary movement will use up valuable energy supplies.
I really feel for my garden birds in winter, when frost if not heavy snow invariably coats my street leading from the Waterworks Valley to South Hobart. And on the coldest days – like the ones we endured earlier this month – I marvel at how the birds survive without the help of both electric heating and the trusty wood stove which keeps the family home warm.
Birds, especially older ones, are at great risk during cold periods because they generally live at the very edge of survival. They do not build, store and use energy in the way mammals do and so extremes in weather – either hot or cold – can be literally a life and death matter. Birds have a far more efficient respiratory system than mammals for the rigorous demands of flying, and this requires vast amounts of energy from food to both keep warm and power flight. In turn, birds have to use far more of their body weight during the course of the day than mammals.
Birds in Tasmania have to survive not only the cold of winter, but even the chill of a non-winter night. Since they don’t store a lot of fat – that is hard to do for a flying creature – it is quite possible for a bird to run out of heat- and energy-producing protein overnight even when it isn’t winter. Beyond migrating to warmer climes, as some of our birds do, there are several things birds do to help them survive the winter. For a start, they wear a layer of down under their feathers for added warmth. Although these are always there, especially in young birds, some species are believed to grow extra down during the cold season. Bird also fluff up their feathers to trap layers of warm air.
Water is the enemy of any creature trying to stay warm and to counter this birds have oil-producing glands which allow them to preen a waterproof coating onto their feathers to avoid the down coats getting wet.
On the coldest of nights, birds can hunker down in a sheltered place like a thick bush or tree canopy with less wind-chill. Some species even huddle together.
Birds also shiver, which helps get added heat from circulation and muscle movement. Another bonus for birds facing the cruel winter is that their feet are covered with scales and have very little cold-damageable tissue in them. They are mostly bone and sinew. Birds may eat more, or selectively eat higher-energy food during the winter and it is here that we can help them.
Although feeding birds is frowned on in some quarters, it can be especially helpful on the coldest of days. Nuts and fruit will help parrots get through the night, and protein like cheese, suet and other fats will aid all species, even if it is contained in a piece of meat or a sausage. A drip feeder with honey or sugar water in it (the sort you can buy in pet shops) will also aid honeyeaters get through the snows of winter.